Among the quadruped heart valves in a human body, the tricuspid valve separates the right atrium (upper chamber) from the right ventricle (lower chamber), and channels the venous blood return to the heart on its way to the lungs. When the venous blood is impelled to the lung arteries, this tricuspid valve closes to block the blood return from backflowing to the atrium and thus provides efficiency to the ejection of blood from the right ventricle that directs the flow towards the lung. In instances where the tricuspid valve is unable to close properly, the pumping pressure of the ventricle can be transmitted in reverse to the atrium and subsequently to the vena cavae. Typically, the superior vena cava functions to bring blood to the heart from the head and the inferior vena cava functions to bring blood to the heart from the liver and other parts of the body (kidneys, gut, legs) that are located below the heart. This pressure can have deleterious effects on the work of the heart and circulatory system. The device herein described provides means of reduction or total nullification of the effects of pressure on the channels of venous return to the heart.
The tricuspid heart valve has an area close to 10 square centimeters, and a circumference approaching 12 centimeters. As the name implies it has three cusps or leaflets that separate to open the valve and allow the venous return from the body to the heart to enter the pumping chamber or right ventricle that redirects the flow towards the lung where venous blood is oxygenated and transformed into arterial blood to supply all tissues of the body. During the pumping action, the tricuspid valve closes to impede retrograde flow into the right atrium.
Acquired disease of the tricuspid valve is much less common than that of the other valves of the heart; this is a reflection of the lower pressures that are experienced by the right chambers of the heart, and thus, the valves of the right side of the heart function generally under less stresses than its left side counterparts. Disease can affect the tricuspid valve mostly in two forms, 1) as tricuspid valve stenosis, a restriction of the opening of the valve, most likely of rheumatic origin, and 2) as tricuspid valve regurgitation or incompetence, generally due to any disease process that causes alterations in the tricuspid valve apparatus that consists of: leaflets, chords, tendinous material that join the leaflet to the muscle of the right-side of the heart, or the annulus (the ring of tissue where the leaflets join the atrium). In the latter, the valve is unable to close completely thus allowing retrograde flow or regurgitation from the ventricle into the atrium.
A small degree of tricuspid regurgitation is found in normal hearts and the prevalence increases with age. Physiologically, the regurgitation is seen as a jet whose velocity is proportional to the pressure differential between the right ventricle and the right atrium. Tricuspid regurgitation (TR) alone may be well tolerated. However, patients suffering from severe TR are troubled with swelling of the legs, pulsations of the jugular vein pulse at the neck due to reverse flow and pressure into the superior vena cava. Other problems associated with severe TR include liver congestion due to reverse pressure to the inferior vena cava and the liver veins, and fatigue and general malaise because of decreased pumping of blood through the heart (that is, decreased cardiac output), that may progress to cardiac cirrhosis and liver dysfunction with prolonged hepatic congestion. Furthermore, high venous pressure may contribute to renal dysfunction and other symptoms of abdominal bloating. All these findings are dependent on the severity of tricuspid regurgitation and pulmonary hypertension. Often the end effect is right heart failure.
Tricuspid regurgitation can be alleviated or eliminated by surgical means, either by replacement of the total valve apparatus with an artificially fabricated replacement tricuspid heart valve, or by constriction of the valve ring with means of an annular remodeling ring (annuloplasty ring). The tricuspid valve repair is not always 100% effective in eliminating the TR, as it has been found in some instances that patients (up to about 15%) who have undergone tricuspid valve annuloplasty may leave the hospital with moderate to severe TR and the tricuspid dysfunction rate may steadily increase to about 30-50%. If surgery is impossible to perform, i.e., if the patient is deemed inoperable or operable only at a too high surgical risk, an alternative possibility is to treat the patient with a stented valvular device and percutaneous means of device delivery for protecting the upper and lower body from high venous pressures.
U.S. Pat. No. 6,503,272 issued on Jan. 7, 2003, entire contents of which are incorporated herein by reference, discloses an artificial venous valve which incorporates a stent having one or more of the elements comprising its frame deformed inwardly towards its center and a biocompatible fabric attached to the one or more elements utilized to replace or supplement incompetent or damaged venous valves.
U.S. Pat. No. 5,855,601 issued on Jan. 5, 1999, entire contents of which are incorporated herein by reference, discloses an artificial venous valve comprising a tubular valve segment containing venous valve means and at least one self-expanding, cylindrical stent member having a plurality of barbs extending from the outer surface of the stent member to engage the natural tissue of the site to hold the valve in place after implantation.
U.S. Pat. No. 6,299,637 issued on Oct. 9, 2001, entire contents of which are incorporated herein by reference, discloses a self expandable prosthetic venous valve comprising a tubular wire support, expandable from a first reduced diameter to a second enlarged diameter, and at least one leaflet pivotably positioned in the flow path for permitting flow in a forward direction and resisting flow in a reverse direction.
U.S. Pat. No. 5,824,061 issued on Oct. 20, 1998, entire contents of which are incorporated herein by reference, discloses an endovascular venous valve prosthesis comprising an endovascular stent assembly including a stent having a generally cylindrical body with a hollow bore extending longitudinally therethrough and first and second support struts formed on opposite sides of the outflow end of the cylindrical body and extending generally longitudinally therefrom; and a preserved segment of vein having an outer wall and a venous valve positioned therein, the valve having two leaflets extending generally longitudinally within the segment of vein with lateral edges adjacent the outer wall.
U.S. Pat. No. 5,607,465 issued on Mar. 4, 1997, entire contents of which are incorporated herein by reference, discloses a valve for use in a blood vessel having a bent flexible wire mesh with elasticity and plasticity so as to be collapsible and implantable remotely at a desired site and a monocusp sail-like valving element mounted onto it.
U.S. Pat. No. 5,997,573 issued on Dec. 7, 1999, entire contents of which are incorporated herein by reference, discloses a dilation restrictor apparatus for limiting the extent to which a blood vessel may dilate adjacent to a point whereat a cut end of the blood vessel has been anastomosed to a venous valve implant, the dilation restrictor apparatus comprising an elongate tubular body having a hollow bore containing a plurality of apertures formed therein to permit passage of fluid therethrough.
U.S. Pat. No. 6,383,193 issued on May 7, 2002, entire contents of which are incorporated herein by reference, discloses a delivery system for the percutaneous insertion of a self-expanding vena cava filter device being formed with a length along a longitudinal filter axis, the system comprising constraining the filter in a compact condition within an elongated, radially flexible and axially stiff tubular member and a displacement member attached to the tubular member for displacing the filter from the segment thereby to deploy the filter.
None of the above-referenced prior art discloses means for protecting the upper body and lower body of a patient from spiked or elevated venous pressure resulting from cardiac tricuspid valve regurgitation.
Therefore, it is one preferred object to provide a method of protecting an upper body and a lower body of a patient from high venous pressures comprising implanting an elongate valve stent having a first valved stent member placed at a superior vena cava and a second valved stent member placed at an inferior vena cava, wherein both stent members are collapsibly expandable and wherein the first and second valved stent members are configured to permit blood flow towards the right atrium of the patient and prevent blood flow in an opposite direction.